Friday

Scientists Have Used Genetically Engineered Poliovirus To Destroy Cancer Cells

With British scientists building an artificial embryo from stem cells and their American counterparts using a modified poliovirus to fight off cancer cells, it looks like science isn't short on achievements this week. An immunotherapy technique developed by researchers in the laboratory of Matthias Gromeier at Duke University, uses an engineered hybrid of poliovirus and rhinovirus to kill off cancer cells.

The technique isn't new as clinical trials started as early as 2011. Moreover, a phase I clinical trial that was launched in 2012 showed promising results. The patients who were part of this trial had a recurring glioblastoma after receiving traditional therapy. Out of the 23 patients who received the so-called optimal dose, 15 are still alive. Furthermore, three patients who were treated early continue to live to more than 36 months after the treatment. Compared to traditional therapy's median survival time, which is 14.6 months, these results offer a great hope for patients with glioblastoma, a type of brain cancer.

The new research, which was published in the journal Science Translational Medicine, explains in details the mechanisms used by ecombinant oncolytic poliovirus (i.e., PVS-RIPO) to destroy cancer cells.

Last year, the technique received a "breakthrough" status from the FDA, meaning it will benefit from accelerated review and enhanced cooperation with the FDA, which could pave the way for its approval.

PVS-RIPO (i.e., the modified poliovirus) works by attaching itself to cancerous cells. The researchers discovered that the virus binds to a special protein called CD155, which is found in abundance in cancerous cells. The virus then infects and damages those malignant cells, triggering the release of antigens. The presence of antigens sets off an alarm signal, prompting the immune system to start attacking them.

The modified poliovirus benevolent acts don't end here, as it infects both the dendritic cells and macrophages. Dendritic cells are antigen-presenting cells, meaning their role is to process and "show" antigens to T-cells which play a very important role in the immune system. Macrophages are a type of white blood cell that does the dirty work of eliminating foreign objects that invade our bodies. Once dendritic cells have been infected by the virus, they stimulate T-cells which in turn start an attack to get rid of the poliovirus-infected tumor.

This process seems to affect both infected and uninfected cancerous cells, and once triggered, it will continue to expose them to the immune system for a long period of time, thus effectively preventing the tumor from regrowing.